Previous epidemiologic and genetic segregation studies of families from southern Louisiana have suggested that in a subset of families a susceptibility allele may exist that acts in conjunction with environmental risk factors (notably smoking) to increase the risk of lung cancer. An existing rapid-surveillance system in 24 southern Louisiana parishes is being used to ascertain recently diagnosed lung cancer patients. Family history and environmental risk factor data are being collected 1) on all patients and 2) on the spouses, first- and second- degree relatives and half-sibs of patients with at least 2 affected relatives. Blood samples and other biological samples (such as formalin- fixed or snap-frozen tissue blocks) are also being collected from 15-20 of these families with at least 2 affected relatives in addition to the initial patient, based on whether the family is likely to be informative for linkage analysis. A set of approximately 10 families ascertained during previous preliminary studies in this population are also being extended and additional biological samples collected to increase the value of these families for linkage analysis. Histopathological confirmation is also being collected on all affected individuals in these 25-30 pedigrees. These data and biological samples will be provided to NIH investigators to be used to search the genome for linkage to a lung cancer susceptibility locus in a timely and efficient manner.